It is known in the art relating to diesel engine cooling systems to provide an engine with one or more centrifugal water pumps, each having a centrifugal flow or mixed flow impeller carried on a shaft and driven by a drive gear or other drive means. The shaft is supported on spaced bearings carried in a housing and lubricated by oil flow from the associated engine oil system. Both ball and roller bearings have been used in the past to carry rotary support loads and axial thrust forces acting on the shaft.
Oil passing through the impeller end bearing is returned to the engine oil sump through a drain line or passage in the water pump housing. A lip-type oil seal is conventionally utilized to prevent oil from passing along the shaft into the water impeller portion of the pump. Similarly, a conventional cartridge-type carbon water seal running against an annular seal surface has been used to prevent the escape of pressurized water from the impeller end of the pump into the oil lubricated portions.